IEEE Trans Med Imaging. 2018 Oct;37(10):2257-2265. doi: 10.1109/TMI.2018.2840827. Epub 2018 May 25.
Measuring cell motility and morphology is important for revealing their functional characteristics. This paper presents automation techniques that enable automated, non-invasive measurement of motility and morphology parameters of single sperm. Compared to the status quo of qualitative estimation of single sperm's motility and morphology manually, the automation techniques provide quantitative data for embryologists to select a single sperm for intracytoplasmic sperm injection. An adapted joint probabilistic data association filter was used for multi-sperm tracking and tackled challenges of identifying sperms that intersect or have small spatial distances. Since the standard differential interference contrast (DIC) imaging method has side illumination effect which causes inherent inhomogeneous image intensity and poses difficulties for accurate sperm morphology measurement, we integrated total variation norm into the quadratic cost function method, which together effectively removed inhomogeneous image intensity and retained sperm's subcellular structures after DIC image reconstruction. In order to relocate the same sperm of interest identified under low magnification after switching to high magnification, coordinate transformation was conducted to handle the changes in the field of view caused by magnification switch. The sperm's position after magnification switch was accurately predicted by accounting for the sperm's swimming motion during magnification switch. Experimental results demonstrated an accuracy of 95.6% in sperm motility measurement and an error <10% in morphology measurement.
测量细胞的运动和形态对于揭示其功能特征非常重要。本文提出了自动化技术，能够自动、非侵入性地测量单个精子的运动和形态参数。与手动定性估计单个精子运动和形态的现状相比，自动化技术为胚胎学家提供了定量数据，以便选择单个精子进行胞浆内精子注射。本文采用自适应联合概率数据关联滤波器进行多精子跟踪，并解决了识别相交或空间距离小的精子的挑战。由于标准微分干涉对比（DIC）成像方法具有侧照明效果，会导致固有不均匀的图像强度，从而给准确的精子形态测量带来困难，因此我们将全变差范数纳入二次代价函数方法中，这两种方法有效地消除了不均匀的图像强度，并在 DIC 图像重建后保留了精子的亚细胞结构。为了在切换至高倍镜后重新定位在低倍镜下识别出的相同感兴趣的精子，我们进行了坐标变换来处理由于放大倍数切换而引起的视场变化。通过考虑在放大倍数切换过程中精子的游动运动，准确地预测了放大倍数切换后的精子位置。实验结果表明，在精子运动测量方面的准确性达到 95.6%，在形态测量方面的误差<10%。
